Need help with adding various colors to BMP File

This is a discussion on Need help with adding various colors to BMP File within the C Programming forums, part of the General Programming Boards category; Ok, so I have a program that essentially takes in a bmp file, and outputs a output bmp. Now, if ...

  1. #1
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    Need help with adding various colors to BMP File

    Ok, so I have a program that essentially takes in a bmp file, and outputs a output bmp. Now, if I did nothing to the input file, then essentially the same file will write as the output file. I have the capability of altering the color of the out file to a single color.But for the life of me,I cant figure out how to add multiples color to the output file. So say for example, if I had a input file that contains the colors red and white. How would I alter it(the input file) to change the color format to say, blue and white. Here is the code I have:

    Code:
       for (int j = 0; j < bi.biWidth; j++)
            {
                // temporary storage
              RGBTRIPLE triple;// RGBTRIPLE is a struct 
              BYTE temp; //BYTE is a struct that is made up of uint8_t.
               
                 char temp2[7]="ff";
             
                
                fread(&triple, sizeof(RGBTRIPLE), 1, inptr);
              
               
                 temp= (BYTE)temp2; 
                 triple.rgbtGreen=temp;
                 triple.rgbtRed=temp;
                 triple.rgbtBlue=00;
               
               
                fwrite(&triple, sizeof(RGBTRIPLE), 1,outptr);
               
            }
    Any help would be greatly apprecitaed. Thanks.

  2. #2
    and the hat of wrongness Salem's Avatar
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    Perhaps
    triple.rgbtGreen=0xff;
    triple.rgbtRed=0xff;
    triple.rgbtBlue=0x00;

    Instead of all that mucking about with strings.
    If you dance barefoot on the broken glass of undefined behaviour, you've got to expect the occasional cut.
    If at first you don't succeed, try writing your phone number on the exam paper.
    I support http://www.ukip.org/ as the first necessary step to a free Europe.

  3. #3
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    I see. But what if I want the file to have a mixture of white included with that yellow. How would I go about implementing that.

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    You could use one of the many HTML color charts, for example

    HTML Color Chart

    Look at the hex codes in the HTML color you like and use those values as your red, green, and blue parts

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    Quote Originally Posted by c99tutorial View Post
    You could use one of the many HTML color charts, for example

    HTML Color Chart

    Look at the hex codes in the HTML color you like and use those values as your red, green, and blue parts
    Cool. So with my code, if I wanted to generate a mixture of white and red, I would just pick a color that does that for me? When glancing at a scanline of pixels on a bmp, I see both red and white hex codes being used. How is that implemented?

  6. #6
    and the hat of wrongness Salem's Avatar
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    Pick a colour
    Say
    Deepskyblue #00BFFF

    Take the appropriate pair of hexadecimal digits.
    Put 0x in front of them in your C code.
    Assign the appropriate members of your colour triple struct.
    If you dance barefoot on the broken glass of undefined behaviour, you've got to expect the occasional cut.
    If at first you don't succeed, try writing your phone number on the exam paper.
    I support http://www.ukip.org/ as the first necessary step to a free Europe.

  7. #7
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    got it, thank you!

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